Difference between CMAKE_PROJECT_NAME and PROJECT_NAME?

Question

What is the difference between CMAKE_PROJECT_NAME and PROJECT_NAME?

From the documentation:

CMAKE_PROJECT_NAME

The name of the current project.

This specifies name of the current project from the closest inherited project() command.

PROJECT_NAME

Name of the project given to the project command.

This is the name given to the most recent project() command.

I don't understand the difference.

When should I use CMAKE_PROJECT_NAME? When should I use PROJECT_NAME?

Answer 1

From the documentation, I don't get the difference between the two variables.

The difference is that CMAKE_PROJECT_NAME is the name from the last project call from the root CMakeLists.txt, while PROJECT_NAME is from the last project call, regardless from the location of the file containing the command.

The difference is recognizable from the following test.

File structure:

|-CMakeLists.txt \-test2   |-CMakeLists.txt   \-test3     \-CMakeLists.txt 

CMakeLists.txt:

cmake_minimum_required(VERSION 3.0) project(A) message("< ${CMAKE_PROJECT_NAME} / ${PROJECT_NAME}") project(B) message("< ${CMAKE_PROJECT_NAME} / ${PROJECT_NAME}") add_subdirectory(test2) message("< ${CMAKE_PROJECT_NAME} / ${PROJECT_NAME}") project(C) message("< ${CMAKE_PROJECT_NAME} / ${PROJECT_NAME}") 

test2/CMakeLists.txt:

project(D) message("<< ${CMAKE_PROJECT_NAME} / ${PROJECT_NAME}") add_subdirectory(test3) project(E) message("<< ${CMAKE_PROJECT_NAME} / ${PROJECT_NAME}") 

test2/test3/CMakeLists.txt:

project(F) message("<<< ${CMAKE_PROJECT_NAME} / ${PROJECT_NAME}") 

The relevant output is:

< A / A < B / B << B / D <<< B / F << B / E < B / B < C / C 

In the sub-directories, always B is the value for CMAKE_PROJECT_NAME.

Answer 2

It may help, if we look at it this way: CMAKE_PROJECT_NAME is a global and PROJECT_NAME is a local name ;)